Which of the following is the correct IUPAC name for a benzene ring with a methyl group at position $1$ and a nitro group at position $3$?

• A. $3$-nitrotoluene
• B. $1$-methyl-$3$-nitrobenzene
• C. m-nitrobenzene
• D. $3$-methyl-$1$-nitrobenzene

Answer: (A)

Verified step by step guidance

1. Identify the parent structure: The base compound is benzene, so the parent name will be 'benzene' or a derivative name if a substituent is considered the parent substituent.
2. Determine the substituents and their positions: There is a methyl group at position 1 and a nitro group at position 3 on the benzene ring.
3. Apply IUPAC numbering rules: Number the ring so that the substituents get the lowest possible numbers. Since the methyl group is at position 1, the nitro group is at position 3.
4. Decide the parent name based on substituent priority: The methyl group (–CH₃) is considered a substituent of benzene, but when present, the compound is often named as 'toluene' (methylbenzene). Nitro is a substituent on toluene.
5. Construct the correct IUPAC name: Name the compound as a derivative of toluene with the nitro group at position 3, resulting in '3-nitrotoluene'.